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Electric Stunt => Gettin all AMP'ed up! => Topic started by: John Castle on January 12, 2012, 02:07:09 PM
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I am working on a 1/2a sized electric and would like to be able to slide the battery into the built up wing. What kind of engineering do you think I should do to be able to remove a section of the leading edge or possibly even the spars from one of the bays next to the profile fuse? Would sheeting an extra bay be enough?
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The spar is what keeps the wing from folding, so removing it isn't a good idea.
I'd try for sliding the battery in just on top of the lower spar; if I could do all this and miss both the control system and the leading edge I'd feel pretty proud of myself.
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I'm wondering the same thing for electric combat planes. I'm inclined to build the battery into the plane and charge it there. Combat planes are a different case, though. One typically goes to the field with a bunch of them, so he could fly and charge them in rotation. I didn't answer your question, did I? I just pontificated and changed the subject, as is my wont.
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I am working on a 1/2a sized electric and would like to be able to slide the battery into the built up wing. What kind of engineering do you think I should do to be able to remove a section of the leading edge or possibly even the spars from one of the bays next to the profile fuse? Would sheeting an extra bay be enough?
Can you elaborate a little on your wing thickness & battery thickness? Here's a couple ideas frim ones I have done:
* Converted a Baby Clown ARF. No room for the pack inside the wing so instead I notched the wing out back to the spars. Added a shear web between the spars and band the battery to the fuse side. It is right on the vertical CG and works great - Hate to find out what will happen in a crash tho!
* Put an in-wing batt box in a Brodak Jr Flite Streak. I had to just barely sand on the inside of the spars so I did not reinforce them directly However for the center section sheeting from the spars forward I used 1/16" basswood instead of balsa. Had to soak it to get the curvature but it worked great. After the wing was assembled I cut out the Leading Edge of the wing and did the final sanding to fit the battery in place.
I have another bird in the to-build pile that will require removing a good size chunk of the 3/16 square (top & bottom) spars. I plan on spanning that gap with a piece of 1/16 ply and using the basswood planking as on the Jr Streak. I may have to plank out 1 bay farther as you suggested too...
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I forgot about the combat plane. Here's a pix of the Brodak Gladiator ARF. I cut a hatch in the bottom covering then was able to cut away the foam holding the built in bladder tube. Did a little more foam removal and I am no able to slip the battery in through the bottom, forward betwen the spars and the battery lies spanwise in the foam - Look closely and you cna just bareley see it in the foam. The velcro strap keeps it from falling back & out. Was able to fit a thin plastic hatch on the bottom.
Depending on your wing you MIGHT be able to install the pack spanwise betwen the spars and the wing LE and avoid removing spar material.
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Reinforce the notched spar with carbon fiber might work.
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Making the spar flatter and wider might sometimes work, but only if you did it during construction. So, for example, 1/2" x 1/8", instead of 1/4" square.
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You might not want to just cut out the spar but . You could reposition it or beef up the part you keep.
Keep in mind the exact size of the battery you need and if it would be thin enough to fit inside the wing with enough space to use some heavier cap strip over the spar.
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Don't forget - batteries need cooling air flow.
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The plan sheet shows how I did the battery compartment on the Ringmaster 150E.
Pat
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I have a couple of Pat King's electric 1/2 A Ringmasters (a Baby and a 150) and for both I shaved off the lower portion of the outboard wing and used a plywood plate for the battery mount. I installed Velcro straps to secure the battery. I know this is NOT inside the wing but you need a pretty thick wing to hide the battery inside (I used 3S batteries so three cells thick). You must install the control horn in the root of the INBOARD wing to leave room for the electronics in the outboard root. I will attach a couple of photos.
By the way this is essentially what Pat King has on his plans for the 150 Ringmaster.
Hope this helps.
John
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The battery mounting design on the electric versions of my Ringmaster 150E and Ringmaster Jr. came from John Cralley. The work well for him and do not seriously weaken the wing.
Pat
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Thanks to everybody for all of the good ideas! I decided to solve my issue by making a built up fuse and hiding the battery in there.
BTW the plane is a modified Pinto with an AXI 2217/16 and a 1000ma battery. I am hoping that the large battery will allow enough time for the whole pattern. It seems that the finished weight will be around 15 oz.
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Thanks to everybody for all of the good ideas! I decided to solve my issue by making a built up fuse and hiding the battery in there.
BTW the plane is a modified Pinto with an AXI 2217/16 and a 1000ma battery. I am hoping that the large battery will allow enough time for the whole pattern. It seems that the finished weight will be around 15 oz.
Tidy packaging!
My 1/2A Pathfinder needs a 1300mah battery on 52' lines, however on 42' it can use a 1000 mah - so I think you will be OK if you keep it to 42's